Various types of foldable ladders are well known in art. Such ladders provide a means for an individual to climb to or reach heights using a free standing ladder in contrast to extension ladders which are braced against a structure when is use.
Ensuring the stability of such a ladder is critical for safety purposes. When the center of gravity of the ladder and user combination falls outside the ladder footprint, any ladder will topple. Thus, the large triangular footprint of a tripod configuration is desirable. However, even tripod configurations can be unstable when used on an uneven flat terrain. This is particularly true when the tripod is not a true tripod in that the legs which bracket the steps both engage the ground as one ridged unit. Such an arrangement means unevenness in any of four points and will cause instability in the ladder.
Various solutions have been devised in attempts to overcome the problem. WIPO Patent Application PCT/US90/07498 entitled IMPROVED TRIPOD LADDER to Baker which published on Jul. 9, 1992 discloses a tripod ladder having legs that rotate about a pivot pin held between rear leg extensions. The legs are maintained in a 120 degrees orientation from one another by lips which form alignment channels.
U.S. Pat. No. 4,524,849 entitled TRIPOD issued on Jun. 25, 1985 to Riddle discloses a tripod ladder for use on uneven ground. The second or third leg portions can be provided in a telescoping or shortening manner on at least one of the legs.
U.S. Pat. No. 3,165,169 entitled LADDER HOLDER issued on Jan. 12, 1965 to Machen discloses a tripod type ladder holder having adjustable leg portions composed of upper tubular leg portions which telescope for adjustment into lower leg portions.
U.S. Pat. No. 3,189,124 entitled LADDER issued on Jun. 15, 1965 to Rateau shows a ladder having a sole which engages the ground.
None of the known prior art disclose the combination set forth herein.